When a law enforcement officer makes an arrest and handcuffs a criminal suspect behind his or her back, the officer must empty the suspect's pockets before putting him in the back of the police car. This is a mandatory procedure in all jurisdictions.
What actually happens is that the officer will search the suspect's pockets and put the contents, contraband and/or other property, on the hood of the patrol car. If there is any wind, or if the items are small, or if there are numerous items, they will often end up on the ground. In this case, the officer has to bend over near the suspect's feet to retrieve any fallen objects. This in itself creates a safety issue for the officer. The officer cannot let go of the prisoner at any time, especially if he is combative or an escape risk.
If the officer has found contraband and loses it, he is in trouble with the force for having lost the evidence. If for example, the officer places property retrieved from pockets and any contraband evidence on the patrol vehicle hood, and the prisoner decides to be combative, in all probability, the evidence and property will be scattered around the surrounding ground area. Any glass item, like a crack cocaine pipe, will more than likely break. If the prisoner has money, it flies away. It is obvious that the circumstances that can lead to lost property and evidence is enumerable and the consequences can be extremely detrimental to the chances of a successful prosecution against the prisoner.
What is needed is a device that is convenient to use by the police officer and that can be used to secure property and evidence while allowing the officer to maintain control of the prisoner.